The overall objective of the proposed research is the characterization of the kinetics of growth and dissolution of synthetic renal stone-forming minerals such as calcium oxalate, uric acid, the urates, calcium phosphates and magnesium ammonium phosphate in supersaturated solutions and in urine. The highly reproducible procedure of seeded growth in stable supersaturated solutions under conditions of sustained supersaturation developed in our laboratory, will be used and a range of ionic strength, concentration and pH typical of those in urines will be studied in order to provide information about the nature of the solid phases formed in the stone-forming process. Emphasis will be placed on the elucidation of the factors controlling the formation of the mixed mineral solid phases (e.g., by epitaxy) found in renal stones; the influence of individual urine components on this process will be investigated. In parallel with these studies, specific surface area, scanning electron microscopic and electron microprobe investigations of the growing crystals will be made in order to relate crystal morphology to the kinetics of the growth process. The constant composition kinetics method will be used to investigate the mineralization behavior of the mono-,di-and tri-hydrates of calcium oxalate urines from normal and stone-forming subjects. Dissolution studies will also be made at controlled undersaturation of both synthetic and natural stone-forming minerals. The information obtained from this proposed study will be helpful in the elucidation of the mechanism of renal stone formation and in the search for new and improved stone inhibitors capable of oral administration in the treatment of urolithiasis.